Lecture 2 Flashcards
What are the two layers of the skin and what are their purpose?
epithelial layer-
waterproof barrier
dermal layer- Supporting layer (if this layer affected by injury, this is where you would see more severe scarring)
Components of the epithelial layer of skin
epithelial layer of skin
- keratinocytes (90%)
- barrier, melanocytes (pigmentation), immune cells
Components of the dermal layer of skin
- Fibroblasts (matrix)
- Endothelial cells (vascular supply)
- Hair follicle cells
What is the multi-step process of response to injury
- Clotting
- Vascular response
- Inflammation (drives wound repair)
- Scar formation
- Epithelial healing
- Contraction
- Scar remodelling
What are the two things to consider when treating burn injuries?
- Amount of SA covered
2. Depth of burn
What is the recommended treatment for total body SA burns?
Donor site availability (inc. SA burn = dec. donor site avail.)
What is the recommended treatment for depth burns?
Intrinsic repair capacity
What are the 4 types of burns?
- Epithelial burns
- Partial thickness burn
- Deep dermal burn
- Full thickness burn
What are the treatments for the 4 types of burns?
- Epithelial burns = conservative
- Partial thickness burn = dermabrade + CEA
- Deep dermal burn = mesh graft + CEA
- Full thickness burn = Integra + mesh graft + CEA
Skin grafts - facts
- Graft taken from patients healthy site
- Skin is meshed to cover large wound
- donor site morbidity
- limited size (1:3 expansion common, max 1:5)
- mesh pattern of healed skin
What is a xenograft skin sources?
- graft from animals, typically pigs, cats, rabbit and mice
- usually not cultured
- vigorous rejection, therefore limited to temporary biological dressing
What are allografts skin sources?
- graft from same species (humans)
- typically cadaveric or neonatal donors
- Eventual rejection due to HLA-DR antigens
- Immunosuppressive therapy must be given to prevent early rejection
- risk of cross contamination
What are cultured epithelial autograft (CEA) sheets?
- cultures using a large, full-thickness biopsy
- cultured as confluent sheets in the lab
- Generally 3-10 cell layers thick
- Clipped to a petrolatum gauze backing
- available 3-5 weeks after initial biopsy
Difficulties = fragility and inability to take
What are the cell types and therapeutic approaches to burns?
- keratinocytes = epithelial cover
- fibroblasts = dermal matrix
- melanocytes
- endothelial cells = revascularisation
What is the scar risk of burn that has 10 days to heal?
4%
What is the scar risk of a burn that has over 21 days to heal?
78%
What is an example of non-cultured skin cell based therapy?
Cell spray
Cell spray skin therapy
- expanding cell no.
- greater coverage of cells from small biopsy
- still involves skin biopsy
- spray @ smaller density –> seed larger area
- promotes healing over larger area quicker
What are the physical characteristics of ECM & dermal scaffold use?
- strength
- stress
What are the biological characteristics of ECM & dermal scaffold use?
- secreted factors
- glycosylation/sugars
Matrices - skin burn therapy
- collagen based (or elastin/collagen - matriderm)
- deep & extensive burns = rapid replacement of dermal template to enhave recovery
- limited by angiogenesis into new template
- matirces = avascular
Laser scar amelioration
= adjunct therapies
- create micro-holes in skin
- creating micro-damage and allowing it to re-heal
- OCT imaging - measure vascularisation
First 48 hours of a burn?
Stabilise, control and plan;
ABC, fluid resuscitation, escarotomies, infection control
Initimate relationship between blood and ____ supply
nerve